Electrical lighting equipment is pervasively used in modern society to generate light energy. The light energy provides illumination by which to illuminate an area.
The illumination provided by the lighting equipment is used, many times, for functional purposes. Activities that require light for their effectuation are able to be performed when the lighting equipment is used to illuminate an appropriate area.
Lighting equipment is sometimes also utilized for aesthetic purposes. That is to say, illumination of an area sometimes also provides aesthetic improvements to the lighted areas, as well as, perhaps also, adjacent areas to the lighted areas. And, the electrical lighting equipment is used to generate light energy to provide illumination that serves both functional and aesthetic purposes.
Electrical light sources convert electrical energy into light energy. A byproduct of the conversion is heat energy. The light energy generated by many conventional electrical light sources appears to be white in color, and the light energy is referred to as being white light. The color of the light energy projected towards a target to illuminate the target might, however, sometimes be preferred to be of a color other than the white color of the white light.
Lighting equipment that is utilized for stage lighting purposes, that is, to illuminate a target on a theatrical, or other, stage, might preferably be of a light colors other than the white light conventionally generated by many conventional electrical light sources that form, conventionally, parts of stage lighting equipment. Other lighting equipment similarly might preferably be of a light color other than the white light of the light energy initially generated by the light source.
To alter the color of the light, a light filter is placed in the path of the light energy, i.e., the light beam, to alter the color of the light. By placing a color filter in the path of transmission of the light energy, the light filter filters a component portion of the light energy, thus altering the color of the light. Through suitable selection of the light filter characteristics, light of a desired color is formed.
Typically, when the lighting equipment is used for stage lighting purposes, the color of light that is desired to illuminate a target changes. That is to say, a sequence, or series, of different light colors are desired to illuminate a target during successive intervals. Change of the light filter characteristics is required to change the light color during the successive intervals. When the lighting equipment is used for stage lighting during a performance, sometimes the light color must be changed many times during a stage performance. When the characteristics are changed, the changes must be effectuated quickly. Light filters that filter components of white light to form the colored light must correspondingly quickly changed.
Most simply, lighting equipment utilized for stage lighting in which the color of the light directed towards a target is to be filtered, manual switching of the light filter is performed each time in which the color of the light is to be changed. A lighting operator positions the filter in the path of the light beam and successively changes the filter, or its characteristics, when the color of the light is to be changed. Each time in which the light color of the light is to be changed, the stage lighting operator is required manually to remove a light filter and replace it with another, or otherwise alter the characteristics of the filter, each time in which a light color change is to be made.
Manual operations are necessarily labor-intensive. Additionally, manual changes are prone to human error. Rehearsal of the light filter change sequence is also typically required of the stage lighting operator to rehearse the necessary changes.
Various apparatus and mechanisms by which to automate the procedure by which to change the light filters are sometimes implemented. For instance, U.S. Pat. No. 6,142,652 discloses a lighting device that includes a light filter having filter elements rotatably positionable in an optical path to filter light projected along the optical path.
Conventional light filters are sometimes formed of a gel material. While effective to form the filters, gel material is susceptible to damage of a prolonged exposure to heat, such as the heat generated as a byproduct of the lighting equipment. While filter elements formed of dichroic materials are available, their use, to date, has been limited. Dichroic filters are advantageous for the reason that such filters do not suffer from the effects of heat degradation to the extent that gel materials do.
If color changing apparatus could be provided that utilizes dichroic filters while permitting the light colors of light generated by lighting equipment to be quickly, and automatically, made, an improved lighting assembly would be provided.
It is in light of this background information related to color-changing lighting equipment that the significant improvements of the present invention have evolved.